Pulmonary vein display in two dimensions

ABSTRACT

A method for data display includes acquiring a three-dimensional (3D) map of a lumen inside a body of a subject, transforming the 3D map of the lumen into a two-dimensional (2D) image by projecting the 3D map onto an annulus, and presenting the 2D image on a display screen.

FIELD OF THE INVENTION

The present invention relates generally to medical ablation procedures,and particularly to the display of a medical ablation procedure.

BACKGROUND

Catheter ablation is a minimally invasive procedure used to remove orterminate a faulty electrical pathway from sections of the heart of apatient who is prone to developing cardiac arrhythmias.

U.S. Patent Application 2013/0123598 describes an MRI-compatiblecatheter, which includes an elongated flexible shaft having oppositedistal and proximal end portions. A handle is attached to the proximalend portion and includes an actuator in communication with the shaftdistal end portion that is configured to articulate the shaft distal endportion. The distal end portion of the shaft may include an ablation tipand includes at least one RF tracking coil positioned adjacent theablation tip that is electrically connected to an MRI scanner. The atleast one RF tracking coil is electrically connected to a circuit thatreduces coupling when the at least one RF tracking coil is exposed to anMRI environment. Each RF tracking coil is a 1-10 turn solenoid coil, andhas a length along the longitudinal direction of the catheter of betweenabout 0.25 mm and about 4 mm.

U.S. Patent Application 2012/0189178 describes a method and an apparatusfor automatically generating an optimal 2-dimensional (2D) medical imagefrom a 3D medical image, at least one virtual plane crossing a 3D volumeis generated from 3D volume image data for showing part of a patient'sbody in a 3D manner, at least one 2D image representing a cross sectionof the part of the patient's body is generated by applying the 3D volumeimage data to the virtual plane, and a 2D image suitable for diagnosisof the patient having a feature most similar to a target feature fromamong the at least one 2D image is output.

U.S. Pat. No. 8,135,185 describes a method of finding the location of anoccluded portion of a blood vessel relative to a three-dimensionalangiographic image of a subject's vasculature includes identifying thelocation of the occluded portion of the blood vessel on each of a seriesof displayed two dimensional images derived from the three dimensionalimage data in planes substantially transverse to direction of theoccluded portion of the vessel. The identified locations in the occludedportion of the vessel can then be used to determine the path of theoccluded portion of the vessel.

U.S. Pat. No. 7,961,924 describes a method and system for determiningthe three-dimensional location and orientation of a medical devicedistal end using a single-plane imaging system, using a computationalmodel of the medical device and a transfer function for the medicaldevice describing local device shape and orientation in response to useror computer determined inputs. The method allows guidance of aninterventional medical system to a set of target points within thepatient using a single-projection imaging system.

SUMMARY

Embodiments of the present invention that are described hereinbelowprovide a method for viewing a lumen of a patient.

There is therefore provided, in accordance with an embodiment of thepresent invention, a method for data display, including acquiring athree-dimensional (3D) map of a lumen inside a body of a subject,transforming the 3D map of the lumen into a two-dimensional (2D) imageby projecting the 3D map onto an annulus, and presenting the 2D image ona display screen.

In a disclosed embodiment, presenting the 2D image includes presenting astationary 2D image.

In some embodiments a 3D image of the 3D map and the stationary 2D imageare simultaneously presented on adjacent parts of the display screen.Additionally or alternatively, the 2D image may be kept stationary whilemanipulating the 3D image.

In a disclosed embodiment acquiring the 3D map includes acquiring a 3Dmap of a lumen undergoing an ablation procedure, wherein the ablationprocedure may include ablating a pulmonary vein of a heart. Additionallyor alternatively, the method includes calculating a path for theablation procedure for a given starting point on the pulmonary vein, anddisplaying an image of the path on a 3D image of the 3D map and on the2D image.

In some embodiments a calculated location and an extent of an ablationlesion are displayed on a 3D image of the 3D map and on the 2D image.Additionally or alternatively, a recommended starting point for afurther ablation is calculated based on at least one of the calculatedlocation and the extent of the ablation lesion, and the method includesdisplaying the recommended starting point as a mark on the 3D image andon the 2D image.

In a further embodiment a completion of the ablation procedure isdetermined in response to presenting an image of a contiguous closedlesion on the 2D image.

There is also provided, in accordance with an embodiment of the presentinvention, an apparatus for displaying data, including a display screenand a processor which is configured to acquire a 3D map of a lumeninside a body of a subject, transform the 3D map of the lumen into a 2Dimage by projecting the 3D map onto an annulus and present the 2D imageon the display screen.

In another embodiment the 2D image is stationary.

In yet another embodiment the processor is configured to present a 3Dimage of the 3D map and the 2D image simultaneously on adjacent parts ofthe display screen. Additionally or alternatively, the processor isconfigured to keep the 2D image stationary while manipulating the 3Dimage.

In still other embodiments the 3D map includes a 3D map of a lumenundergoing an ablation procedure, and the ablation procedure may includeablating a pulmonary vein of a heart. Additionally or alternatively, theprocessor is configured to calculate a path for the ablation procedurefor a given starting point on the pulmonary vein, and to display animage of the path on a 3D image of the 3D map and on the 2D image.

In another embodiment the processor is configured to display acalculated location and an extent of an ablation lesion on a 3D image ofthe 3D map and on the 2D image. Additionally or alternatively, theprocessor is configured to calculate a recommended starting point for afurther ablation based on at least one of the calculated location andthe extent of the ablation lesion, and to display the recommendedstarting point as a mark on the 3D image and on the 2D image.

In an embodiment the processor is configured to determine a completionof the ablation procedure in response to presenting an image of acontinuous closed lesion on the 2D image.

The present invention will be more fully understood from the followingdetailed description of the embodiments thereof, taken together with thedrawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an ablation procedure of apulmonary vein, according to an embodiment of the present invention; and

FIGS. 2-8 show a display screen as seen by a surgeon during an ablationprocedure of a pulmonary vein of a subject, in accordance with anembodiment of the invention.

OVERVIEW

One of the problems during a catheter ablation procedure, such asablation of the pulmonary vein, is visualization of the procedure.Typically, the pulmonary vein is presented as a three-dimensional (3D)image, and as a surgeon performs the ablation he/she re-positions and/orrotates and/or changes the magnification of the image to observe theprogress of the procedure. Surgeons using this method for tracking theprocedure have found the use and manipulation of a 3D image, typicallywhile ablating, both complicated and difficult to execute efficiently.

An embodiment of the present invention solves this problem by acquiringa 3D map of a lumen, such as the pulmonary vein, that is inside a bodyof a subject. The 3D map is transformed into a two-dimensional (2D)image by projecting the 3D map onto an annulus, and the 2D image ispresented to the surgeon on a display screen.

Using this method, the surgeon is able to view and manipulate a 3D imageof a region of an ablation, as described above, while beingsimultaneously presented with a stationary two-dimensional (2D) image ofthe region.

In one embodiment, in the ablation of a pulmonary vein, the region ofablation comprises a cylindrical structure. A processor acquiring the 3Dimage transforms this cylindrical structure into a 2D annulus, with thetwo edges of the cylindrical structure transformed into the inner andouter circumferences of the annulus, and the area of the cylindricalstructure transformed into the area of the annulus. The display screenthat the surgeon observes during the ablation procedure, is divided intotwo areas: The manipulable 3D image of the region of ablation, togetherwith other parts of the heart, is displayed in one area of the displayscreen, whereas the stationary 2D annulus is displayed in the otherarea.

In another embodiment, once the surgeon has determined the startingpoint of the ablation, the processor calculates, based on this startingpoint and on the known geometry of the pulmonary vein, a recommendedpath for the ablation procedure. This path is marked both in the 3Dimage and in the 2D annulus in order to guide the surgeon. Therecommended path is a path around the pulmonary vein, such that, whenthe ablation procedure has been completed, a heartbeat activation wavewill be blocked.

In yet another embodiment, while an ablation lesion is growing duringthe procedure, the processor calculates the locations where the surgeonshould start the next ablation lesion in order to ensure the eliminationof any gaps between the ablation lesions. There will usually be two suchlocations, one on either side of the existing ablation lesions. Theselocations are marked on both the 3D image and the 2D annulus, and theyare re-calculated and moved as the ablation lesions grow.

In a disclosed embodiment, the dimensions of any given ablation lesionis calculated by the processor, using measurements of force exerted bythe tip of the catheter, the radio-frequency power emitted from the tipof the catheter, and the elapsed time for the lesion. In a successfulablation procedure, the surgeon sees a contiguous chain of calculatedimages of ablation lesions growing around the pulmonary vein, until acomplete ring of ablation lesions has been formed. The visualization ofboth the progress and the completeness of the ring of calculated imagesof ablation lesions is greatly facilitated by the display of the 2Dannulus, as the entire ablated region can be seen at once.

SYSTEM DESCRIPTION

FIG. 1 is a schematic illustration of an invasive medical procedureusing apparatus 12, according to an embodiment of the present invention.The procedure is performed by a surgeon 14, and, by way of example, theprocedure in the description hereinbelow is assumed to comprise ablationof a portion of a pulmonary vein 16 of a heart 46 of a human patient 18.However, it will be understood that embodiments of the present inventionare not just applicable to this specific procedure, and may includesubstantially any procedure on biological tissue.

In order to perform the ablation, surgeon 14 inserts a probe 20,typically a catheter, into a lumen of the patient, so that a distal end22 of the probe enters pulmonary vein 16 of the patient. Distal end 22comprises electrodes 24 mounted on the outside of the distal end, theelectrodes contacting respective locations of pulmonary vein 16. Aproximal end 28 of probe 20 is coupled to a console 32 of apparatus 12.

Apparatus 12 is controlled by a processor 30, which is located inconsole 32. Console 32 comprises controls 34 which are used by surgeon14 to communicate with processor 30. During the procedure, processor 30typically tracks a location and an orientation of distal end 22 of theprobe, using any method known in the art. For example, processor 30 mayuse a magnetic tracking method, wherein magnetic transmitters externalto patient 18 generate signals in coils positioned in distal end 22. TheCarto® system produced by Biosense Webster, of Diamond Bar, Calif., usessuch a tracking method.

The software for processor 30 may be downloaded to the processor inelectronic form, over a network, for example. Alternatively oradditionally, the software may be provided on non-transitory tangiblemedia, such as optical, magnetic, or electronic storage media. Processor30 is coupled to a display screen 36, which is divided into a leftdisplay 38 and a right display 40, as is detailed below. While forsimplicity the description herein assumes that the screen is dividedinto a left and a right display, it will be understood that the scope ofthe present invention includes any other convenient method for screendivision and image display, such as an upper and lower display, or afirst screen and a separate second screen.

In order to operate apparatus 12, processor 30 communicates withelectronics 42, which has a number of modules used by the processor tooperate the apparatus. Thus, electronics 42 comprises modules such as anablation module 43, a force module 45 for measuring the force on distalend 22, and a tracking module 47 for operating the tracking method usedby processor 30. The modules may comprise hardware as well as softwareelements. Proximal end 28 of probe 20, coupled to console 32, is furthercoupled to the modules of electronics 42.

Processor 30 uses results of measurements from the modules, such as aforce exerted by tip 44 of distal end 22, a radio-frequency poweremitted from the tip, an elapsed time of the ablation, and a location ofthe tip, to calculate and to display graphically the progress of theablation procedure on display screen 36, as is detailed below.

FIGS. 2-8 show, with reference to FIG. 1, display screen 36 as seen bysurgeon 14 during an ablation procedure of pulmonary vein 16 of patient18, in accordance with embodiments of the invention. Left display 38shows 3D images of pulmonary vein 16 and heart 46 of patient 18, andright display 40 shows a 2D image of a selected portion of pulmonaryvein 16. As is described below, the 3D image in left display 38 istypically manipulable, while the 2D image in right display 40 istypically stationary. Corresponding items in left display 38 and rightdisplay 40 are labelled with the same number, with letter “L” and “R”indicating left and right display, respectively. Display screen 36 maydisplay additional information relating to the ablation procedure, forexample, an elapsed time, and a power dissipated by electrodesperforming the ablation. For simplicity, such additional information isnot presented in the figures.

FIG. 2 illustrates in left display 38 a 3D image 50 of heart 46 and a 3Dimage 52 of pulmonary vein 16 of heart 46. A cylindrical region 54 ofimage 52 corresponds to the region of pulmonary vein 16 where surgeon 14implements the ablation procedure. During the procedure, processor 30projects cylindrical region 54 to a 2D annulus 56 in right display 40,with an edge 58, proximal to image 50, of cylindrical region 54,projected to an inner circumference 60 of annulus 56, and an edge 62,distal to image 50, projected to an outer circumference 64 of annulus56. Surgeon 14 has positioned tip 44 of probe 20 to touch pulmonary vein16, with the position indicated in left display 38 by a fiducial 66L,and in right display 40 by a fiducial 66R. Fiducials 66L and 66R, andthe other fiducials referred to hereinbelow, are typically presented onscreen 36 as icons corresponding to tip 44.

FIG. 3 illustrates display screen 36 after surgeon 14 has selected astarting point for tip 44 to begin ablation, but before initiating theablation. Fiducials 68L and 68R indicate the selected starting point ofthe ablation in left display 38 and right display 40, respectively. Oncethe starting point is selected, processor 30 calculates a recommendedclosed ablation path based on the starting point and the known 3Ddimensions of pulmonary vein 16. The recommended closed path iscalculated based on criteria chosen by surgeon 14, with the criteriabeing, for example, that the closed path is a shortest path around thepulmonary vein, or that the closed path is a fixed distance from thebase of the pulmonary vein. The recommended closed path is displayed asregions 70L and 70R in left display 38 and right display 40,respectively. Region 70L is a band within image 54, corresponding to arecommended path around pulmonary vein 16, and region 70R is a ringwithin annulus 56. Within each of regions 70L and 70R there is marked anarrower ring 71L and 71R further assisting surgeon 14 in directing theablation procedure. Ring 71L and 71R are optimal paths for the ablation,and the width of regions 70L and 70R are typically set by surgeon 14based on the maximum distance he/she is willing to deviate from rings71L and 71R. The recommended ablation path is a closed path aroundpulmonary vein 16, such that, when the ablation procedure has beencompleted, a heartbeat activation wave is blocked.

FIG. 4 illustrates display screen 36 at the start of the ablation. Leftdisplay 38 and right display 40 show calculated ablation lesion images72L and 72R for the first ablation growing, with reference to FIG. 3,from starting point fiducials 68L and 68R, respectively. On screen 36images of different elements are typically differentiated by differentcolors. In the figures of the present application, images of differentelements are differentiated by different types of shading. Thus,completed ablation lesion regions may be imaged as red on screen 36, andare shown has cross-hatched in the figures.

The dimensions of lesion images 72L and 72R are calculated by processor30, using measurements of force exerted by tip 44, radio-frequency poweremitted from the tip, and elapsed ablation time. In addition, processor30 calculates two next recommended ablation positions in regions 70L and70R and shows them as marks 74L and 76L on left display 38 and as marks74R and 76R on right display 40. The next recommended ablation positionsprovide the surgeon with two optional starting positions for asubsequent ablation. In a disclosed embodiment these positions arecalculated to be a fixed distance from the edge of outermost ablations.The fixed distance may be chosen by surgeon 14. In one embodiment thefixed distance has a default value of 3 mm, but the distance may besmaller or larger than this value.

The next recommended positions depend on the location and size of theablation lesion. Surgeon 14 may slide tip 44 along the pulmonary vein,and simultaneously ablate using the tip. Alternatively or additionally,the surgeon may keep the tip stationary while ablating. In either case,as the ablation lesion grows, the next recommended positions arere-calculated and “pushed out.” The images presented on screen 36 aregenerated in real-time, and surgeon 14 is aided by the real-timepresentation of the lesion images 72L and 72R on the two displays.Surgeon 14 terminates the ablation based on his/her judgment and theimages on screen 36, but no later than when the ablation lesion imageson screen 36 reach the edge of regions 70L and 70R. Both the real-timevisualization of the ablation lesions and the indication of nextablation positions are applied continuously in the ablation procedure.

Referring back to FIGS. 2 and 3, it is apparent in left display 38 thatsurgeon 14 has rotated, using controls 34, the 3D image as the ablationprocedure progresses. However, during this rotation, processor 30ensures that annulus 56 in right display 40 remains stationary, thusaiding surgeon 14 in an easy and fast observation of the progress of theablation procedure. It is of great help for surgeon 14 to be able torotate or otherwise manipulate the 3D image at will in left display 38,while at the same time observing a fully stationary 2D image in rightdisplay 40.

FIG. 5 illustrates display screen 36 at the completion of the firstablation lesion, displayed as lesion images 72L and 72R, and the startof a second ablation lesion, shown as lesion images 78L and 78R. Thesecond ablation is implemented at the “upper” recommended next position,shown as marks 76L and 76R, respectively, in FIG. 4. Since the ablationprocedure is continuing, processor 30 calculates new recommended nextpositions. Thus, processor 30 calculates a new, shifted upperrecommended next position to reflect the presence of a second ablationlesion, and displays it as marks 80L and 80R. The “lower” recommendednext position 74L, 74R is not changed.

FIG. 6 illustrates display screen 36 after the first ablation lesion,shown as lesion images 72L and 72R, and the second ablation lesion,shown as lesion images 78L and 78R, have reached their final sizes,melding into each other, and a third ablation lesion, shown as lesionimages 82L and 82R, has started forming. In this case processor 30changes the position of the lower recommended position to a new position83L, 83R, while leaving the position of the upper recommended position80L, 80R unchanged.

FIG. 7 illustrates on display screen 36 the progress of the ablationprocedure, when over half of the circumference of pulmonary vein 16 hasbeen covered by a contiguous ablation lesion, shown as lesion images 84Land 84R, respectively. The advantage of displaying the 2D image on rightdisplay 40, as compared with the 3D image on left display 38, for arapid and easy assessment of the progress of the ablation procedure, isclearly seen. As is illustrated in the figure, 2D image lesion 84Rdisplays the complete contiguous lesion, position 83R and anotherrecommended ablation position 85R, whereas in 3D image 84L only aportion of the lesion, and one of the recommended ablation positions85L, are visible.

FIG. 8 illustrates the completed ablation lesion, shown as lesion images86L and 86R. Both images display as closed paths, corresponding to theclosed recommended path around the pulmonary vein illustrated in FIG. 3.However, the contiguity of the lesion is immediately visible andverifiable in the 2D image of right display 40, whereas the 3D image ofleft display 38 requires manipulation in order to verify the lesioncontiguity.

It will be appreciated that the embodiments described above are cited byway of example, and that the present invention is not limited to whathas been particularly shown and described hereinabove. Rather, the scopeof the present invention includes both combinations and subcombinationsof the various features described hereinabove, as well as variations andmodifications thereof which would occur to persons skilled in the artupon reading the foregoing description and which are not disclosed inthe prior art.

The invention claimed is:
 1. A method for controlling display of dataduring a medical procedure, the method comprising: acquiring locationsignals indicating a location of a probe in a three-dimensional (3D)space, including a lumen, inside a body of a subject, the lumenextending lengthwise between a first circumferential edge and a secondcircumferential edge; presenting a 3D map of the 3D space including thelumen and the location of the probe at a portion of the lumen;transforming the 3D map of the lumen into a two-dimensional (2D) imageby projecting the 3D map of the lumen onto a 2D annulus, the annuluscomprising an inner circumferential edge corresponding to the firstcircumferential edge of the lumen in the 3D space and an outercircumferential edge corresponding to the second circumferential edge ofthe lumen in the 3D space; presenting the 2D image of the annulus on adisplay screen including the location of the probe at a portion of theannulus between the inner circumferential edge and the outercircumferential edge; presenting the location of one or more ablationlesions, presented on the 3D map, on the 2D image of the annulus;calculating an ablation path for the one or more ablation lesions on thelumen; and displaying the ablation path between the firstcircumferential edge and the second circumferential edge on the lumen onthe 3D map and between the inner circumferential edge and the outercircumferential edge on the 2D image of the annulus.
 2. The methodaccording to claim 1, wherein presenting the 2D image comprisespresenting a stationary 2D image of the annulus.
 3. The method accordingto claim 2, comprising presenting the 3D map and the stationary 2D imagesimultaneously on adjacent parts of the display screen.
 4. The methodaccording to claim 3, comprising maintaining the 2D image of the annulusas a stationary image while manipulating the 3D the lumen in one or moredirections on the 3D map.
 5. The method according to claim 1, whereinthe lumen is a pulmonary vein of a heart.
 6. The method according toclaim 5, further comprising determining a completion of an ablationprocedure in response to presenting an image of a contiguous closedlesion on the 2D image of the annulus.
 7. The method according to claim1, further comprising: calculating a starting point for a furtherablation lesion based on at least one of a calculated location of aprevious ablation lesion and an extent of the further ablation lesion;and displaying the starting point as a mark on the lumen on the 3D mapand on the 2D image of the annulus.
 8. A processing and displayapparatus for use in a medical procedure, comprising: a display screen;and a processor which is configured to: acquire location signalsindicating a location of a probe in a three-dimensional (3D) space,including a lumen, inside a body of a subject, the lumen extendinglengthwise between a first circumferential edge and a secondcircumferential edge; present a 3D map of the 3D space, including thelumen and the location of the probe at a portion of the lumen, on thedisplay screen; transform the 3D map of the lumen into a 2D image byprojecting the 3D map of the lumen onto a 2D annulus, the annuluscomprising an inner circumferential edge corresponding to the firstcircumferential edge of the lumen in the 3D space and an outercircumferential edge corresponding to the second circumferential edge ofthe lumen in the 3D space; present the 2D image of the annulus on thedisplay screen including the location of the probe at a portion of theannulus between the inner circumferential edge and the outercircumferential edge; calculate an ablation path for the one or moreablation lesions on the lumen, and display the ablation path between thefirst circumferential edge and the second circumferential edge on thelumen on the 3D map and between the inner circumferential edge and theouter circumferential edge on the 2D image of the annulus.
 9. Theapparatus according to claim 8, wherein the 2D image of the annulus isstationary.
 10. The apparatus according to claim 8, wherein theprocessor is configured to present the 3D map and the stationary 2Dimage simultaneously on adjacent parts of the display screen.
 11. Theapparatus according to claim 10, wherein the processor is configured tomaintain the 2D image of the annulus as a stationary image whilemanipulating the 3D the lumen in one or more directions on the 3D map.12. The apparatus according to claim 8, wherein the lumen is a pulmonaryvein of a heart.
 13. The apparatus according to claim 12, wherein theprocessor is configured to determine a completion of an ablationprocedure in response to presenting an image of a continuous closedlesion on the 2D image of the annulus.
 14. The apparatus according toclaim 8, wherein the processor is configured to: calculate a startingpoint for a further ablation lesion based on at least one of acalculated location of a previous ablation lesion and an extent of thefurther ablation lesion, and display the starting point as a mark on thelumen on the 3D map and on the 2D image of the annulus.
 15. Anon-transitory computer readable medium having instructions for causinga computer to perform a method of controlling display of data during amedical procedure, the method comprising: acquiring location signalsindicating a location of a probe in a three-dimensional (3D) space,including a lumen, inside a body of a subject, the lumen extendinglengthwise between a first circumferential edge and a secondcircumferential edge; presenting a 3D map of the 3D space including thelumen and the location of the probe at a portion of the lumen;transforming the 3D map of the lumen into a two-dimensional (2D) imageby projecting the 3D map of the lumen onto a 2D annulus, the annuluscomprising an inner circumferential edge corresponding to the firstcircumferential edge of the lumen in the 3D space and an outercircumferential edge corresponding to the second circumferential edge ofthe lumen in the 3D space; and presenting the 2D image of the annulus ona display screen including the location of the probe at a portion of theannulus between the inner circumferential edge and the outercircumferential edge; presenting the location of one or more ablationlesions, presented on the 3D map, on the 2D image of the annulus;calculating an ablation path for the one or more ablation lesions on thelumen; and displaying the ablation path between the firstcircumferential edge and the second circumferential edge on the lumen onthe 3D map and between the inner circumferential edge and the outercircumferential edge on the 2D image of the annulus.